Assertion : The inner part of cerebral hemisphere is called white matter.
Reason : Fibres of the tracts are covered with the myelin sheath, which constitute the inner part of cerebral hemisphere. There give an opaque white appearance.

Options

A. If both assertion and reason are true and the reason is the correct explanation of the assertion.
B. If both assertion and reason are true but reason is not the correct explanation of the assertion.
C. If assertion is true but reason is false.
D. If both assertion and reason are false.

Explanation

To analyze the given question, we need to evaluate both the assertion and the reason provided.

### Step-by-Step Solution:

1. **Understanding the Assertion**:
- The assertion states that "The inner part of the cerebral hemisphere is called white matter."
- This is correct. The cerebral hemispheres consist of two types of tissue: gray matter (outer layer) and white matter (inner layer).

2. **Understanding the Reason**:
- The reason states that "Fibres of the tracts are covered with the myelin sheath, which constitute the inner part of the cerebral hemisphere. They give an opaque white appearance."
- This statement is also correct. White matter is primarily composed of myelinated axons (nerve fibers), and the myelin sheath gives the white matter its characteristic white color.

3. **Evaluating the Relationship**:
- The reason explains why the assertion is true. The presence of myelinated fibers in the inner part of the cerebral hemisphere indeed contributes to its classification as white matter and its appearance.

4. **Conclusion**:
- Both the assertion and the reason are correct, and the reason correctly explains the assertion. Therefore, the correct answer is that both statements are true, and the reason supports the assertion.

### Final Answer:
Both the assertion and reason are correct, and the reason correctly explains the assertion.